It has long been recognized that the properties of polymers can be controlled to a high degree through variables such as morphology, composition, thermodynamics and processing conditions. It is similarly known that various sizes and shapes of fillers (e.g. calcium carbonate, silica, carbon black, etc.) can be incorporated into a polymer to somewhat control both polymer morphology and the resulting physical properties. Further it is known that metals are utilized to catalyze the cure (connectivity) of polymeric chains. The resulting physical properties of polymers can be controlled by the nature of the catalyst, the extent of cure, and the mechanism of cure. For example, it is well known that polyurethanes, silicones, vinyl esters, and polydienes are commonly cured through the formation of chemical crosslinks catalyzed by metals. Additionally, it is known that bismaleimides, phenolics, novolacs, dienes, and vinyl polymers can be cured through the assistance of metal catalysts.
Recent developments in nanoscience have now enabled the ability to cost effectively manufacture bulk quantities of materials that are best described as metallized nanostructured chemicals due to their specific and precise chemical formula, hybrid (inorganic-organic) chemical composition, and large physical size relative to the size of traditional chemical molecules (0.3-0.5 nm) and relative to larger sized traditional fillers (>50 nm) Nanostructured chemicals containing catalytically active metals behave as both fillers and catalysts to promote the connectivity of polymer chains between themselves and with fillers and surfaces and with the nanostructured chemical.
Nanostructured chemicals are best exemplified by those based on low-cost Polyhedral Oligomeric Silsesquioxanes (POSS) and Polyhedral Oligomeric Silicates (POS). FIG. 1 illustrates some representative examples of metallized nanostructured chemicals for which the all silicon containing systems are known as POSS and metallized systems are known as POMS. POMS (polyhedral oligomeric metallosesquioxanes) are cages that contain one or more metals inside or outside the central cage framework. In certain instances cages may contain more than one metal atom, more than one type of metal atom, or even metal alloys.
Like the all silicon containing POSS cages, POMS contain hybrid (i.e. organic-inorganic) compositions contain internal frameworks that are primarily comprised of inorganic silicon-oxygen bonds but which also contain one or more metal atoms bound to or inside of the cage (FIG. 2). In addition to the metal and silicon-oxygen framework, the exterior of a POMS nanostructured chemical is covered by both reactive and nonreactive organic functionalities (R), which ensure compatibility and tailorability of the nanostructure with organic polymers. These and other properties of metallized nanostructured POSS chemicals are discussed in detail in U.S. Pat. No. 5,589,562. Unlike metal or other particulate fillers, these metallized nanostructured chemicals have molecular diameters that can range from 0.5 nm to 5.0 nm, are of low density (>2.5 g/ml), highly dispersable into polymers and solvents, exhibit excellent inherent fire retardancy, and possess unique optical and electronic properties.
Prior art associated with fillers, plasticizers, catalysts, and polymer morphology has not been able to adequately control polymer chain, coil and segmental motion, extent of cure, or optical and electronic properties at a molecular level. Therefore, there exists a need for appropriately sized reinforcements for polymer systems with controlled diameters (nanodimensions) and distributions, and with tailorable chemical functionality.